In a network, in particular in a telecommunication network, several network apparatuses may be movable and other network apparatuses may be locally fixed. A movable network apparatus may be in particular a mobile station, such as a mobile phone. A locally fixed network apparatus may be in particular a service station, such as a base station. The base station may be connected with the mobile station in order to perform one or more network services such as performing a telephone conversation or sending video data. The base station may be a serving base station for the mobile station, meaning the base station may provide the service for the mobile station.
The mobile station may move within the network, which may cause a change of the quality of the connection between the serving base station and the mobile station. In such a situation the mobile station or the serving base station may initiate a handover procedure in order to maintain a quality of service, such as the telephone conversation. A handover procedure may also be initiated when the base station may be overloaded, for example caused by several mobile stations to be served by that base station.
In a handover procedure the mobile station may change the base station to which it may be connected while maintaining the provided network service of the network. A handover may be performed for example by providing a connection from the mobile station to an other base station, in particular to a target base station, and to disconnect the connection between the current serving base station and the mobile station.
In such a handover procedure an interruption may occur. The mobile station may be disconnected from the serving base station, but may not yet be connected to a target base station at that moment. This interruption may reduce the quality of service in the network and in particular, the interruption may cause an interrupt of the service provided to the mobile station by the network.
The document WiMAX™ Forum Network Architecture, Stage 3: Detailed Protocols and Procedures, NWG Release 1, Version 1.3.0, Sep. 21, 2008 may describe procedures, call flows, messages, timers, TLV and attributes for the WiMAX™ end-to-end network specification.
The document WiMAX™ Forum Network Architecture, Stage 2: Architecture Tenets, Reference Model and Reference Points, Part 0, Release 1, Version 1.2, Jan. 11, 2008, may describe architecture reference model, reference points and procedures for different end-to-end architecture aspects of WiMAX™ NWG.
The document IEEE 802.16 Broadband Wireless Access Working Group IEEE C802.16maint-08/013r10, Apr. 30, 2008, “Support of load balancing to enhance service availability” may describe load balancing scheme during initial network entry, HO, or re-entry from idle mode.
The standard document IEEE P802.16Rev2/D7 “Air Interface for Broadband Wireless Access Systems”, October 2008, may describe air interfaces.
There may be a need to provide an efficient handover.